This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In this study, we have been studying the role of the brain stem and cerebellum in the production of head-unrestrained gaze shifts from one object of interest to another. Such gaze shifts are composed of an eye saccade and a head movement. There are 3 studies within this project. First, we have finished analyzing the behavior of brain stem neurons that discharge a burst of action potentials with normal head unrestrained gaze shifts. The duration and number of spikes in the burst are best correlated with the eye movement component of the gaze shift. Second, because the eye component and overall gaze shift are tightly correlated in normal gaze shifts, we dissociated them by plugging the semicircular canals, which deliver a signal related to head movement to the brain stem. Under these conditions, the eye saccade always ends before the gaze lands and the head carries the eye the rest of the way. In this situation, the burst is unambiguously related to the eye saccade. Finally, we recorded from the part of the cerebellum whose neurons project to the burst generator. Neurons there have discharge patterns that help accelerate gaze shifts in one horizontal direction and decelerate them in the other. Moreover, the bursts of those neurons are tightly timed with the end of the gaze shift and probably are instrumental in insuring that the gaze stops at the appropriate time to land on target.